/*
 * Copyright 2023 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package androidx.benchmark.vmtrace;

import androidx.annotation.NonNull;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

class ByteBufferUtil {

    private ByteBufferUtil() {
    }

    @NonNull
    public static ByteBuffer mapFile(@NonNull File f, long offset, @NonNull ByteOrder byteOrder)
            throws IOException {
        FileInputStream dataFile = new FileInputStream(f);
        try {
            FileChannel fc = dataFile.getChannel();
            MappedByteBuffer buffer = fc.map(FileChannel.MapMode.READ_ONLY, offset,
                    f.length() - offset);
            buffer.order(byteOrder);
            return buffer;
        } finally {
            dataFile.close(); // this *also* closes the associated channel, fc
        }
    }
}
